Cochlear Implant Sound Processor With Permanently Integrated Replenishable Power Source

ABSTRACT

A cochlear implant sound processor is powered by a rechargeable battery that is permanently integrated into the sound processor. The sound processor contains an inductive coil that may be tuned to an external charging coil for battery recharging. The electronic circuits and coil of the sound processor are housed in a material transparent to RF signals. The sound processor may be placed in a recharging base station in which the sound processor is positioned in a space surrounded by the inductive charging coil embedded in a material transparent to RF signals. The inductive charging coil sends power to the coil inside the processor and thereby recharges the battery. An alternative embodiment utilizes contacts in the sound processor case and aligned terminals in the recharging base station that allow direct charging of the battery.

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/417,973, filed Oct. 11, 2002, which applicationis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to hearing aid prosthesis devices, and, ina preferred embodiment, to a cochlear implant system having an externalsound processor with a permanently integrated replenishable powersource, e.g., a rechargeable battery.

BACKGROUND OF THE INVENTION

All contemporary cochlear implant systems require two separatecomponents: (1) an implant that is implanted in the skull, and (2) asound (or speech) processor that resembles a hearing aid and is worn onthe outside of the body. The two components are linked through RFcommunication, and operating power for the implant is supplied by thesound processor and transmitted inductively.

The power source in the sound processor consists of either rechargeableor primary batteries. Typical battery operating times for currentcochlear implant systems are between 4 hours and 3 days. When batterypower is depleted, the cochlear implant user has to physically removethe empty battery from the sound processor and replace it with a newone. This creates several problems:

-   -   (1) The small size of the batteries requires good manual        dexterity for changing them, which is a problem especially for        the many cochlear implant users who are elderly.    -   (2) Batteries are a choking hazard for small children.    -   (3) Cochlear implant users have to carry spare batteries with        them at all or most times.    -   (4) The sound processor has to contain a battery compartment        that can be either removed entirely for recharging, or that has        to have a mechanical latch or door for replacement of the        batteries. The mechanical components required increase the size        of the processor, and contribute a potential failure mechanism.

It is thus apparent that what is needed is a sound processor for usewith a cochlear implant system, or other hearing-aid system, that avoidsor minimizes the above-problems.

SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by providing acochlear implant sound processor that is powered by a rechargeablebattery that is permanently integrated into the sound processor. Thesize and capacity of the battery is such that operating time of thesystem exceeds a full day. The sound processor contains an inductivecoil that may be tuned to an external charging coil when therechargeable battery needs to be recharged. The material in which theelectronic circuits and coil of the sound processor are housed, e.g.,plastic, epoxy, or ceramic, is transparent to RF signals. Duringnighttime, the sound processor is placed in a recharging base station inwhich the sound processor is positioned in a space surrounded by theinductive charging coil, which coil is also embedded in a material thatis transparent to RF signals. The inductive charging coil sends power tothe coil inside the processor and thereby recharges the battery.Alternatively, or conjunctively, the sound processor contains aconnector, or contacts, that allow direct connection with an externalcharging source, e.g., the charging source within the base station, whenthe rechargeable battery needs to be recharged. Advantageously, thecochlear implant user never has to remove or handle the batterydirectly, and the need for a battery compartment and/or batteryconnection mechanism is eliminated.

Additionally, the inductive coil embedded in the sound processor canalso be used for sending programming information to the programmingdevice, e.g., a laptop computer or other processor in which appropriateprogramming software has been loaded, thereby eliminating the need for aphysical programming connector on the sound processor.

Advantageously, the sound processor may be controlled through use of asmall remote control that communicates with the circuits inside of thesound processor via an RF and/or magnetic link, thereby eliminating theneed for manual controls (switches, buttons, dials, etc.) on the soundprocessor. This further allows the case of the sound processor to beeffectively closed, or sealed, thereby preventing (or at leastminimizing) foreign contaminating particles, e.g., dust or moisture,from entering the sound processor.

A sound processor that has its own integrated power source and theability to be recharged and programmed through RF in accordance with thepresent invention may be worn or carried in several locations outsidethe body, including behind the ear, clipped to the users hair or articleof clothing, hanging from a necklace, carried in a shirt or blousepocket, etc. Alternatively, such a sound processor may be implanted inthe skull alongside the currently implanted electronic portion of thecochlear implant system.

A sound processor having its own integrated power source in accordancewith the present invention also advantageously avoids the need toreplace small batteries, or adjust small controls on the device, therebyeliminating the need for good manual dexterity in use of the device. Asa result, the device is much more user friendly for the elderly orothers who lack good manual dexterity.

A sound processor having its own integrated power source in accordancewith the present invention further eliminates the need for the user tocarry spare batteries. Moreover, because no batteries of any kind areneeded (except for the remote control, which may be of the conventionalAA or AAA size, and are long-lasting), there are no spare or otherbatteries lying around which could pose a choking hazard for youngchildren.

Finally, a sound processor having its own integrated power source inaccordance with the present invention may be made much smaller and bemore reliable than equivalent units that use replaceable batteries.According to the present invention, the extra components needed tosupport a removable battery—mechanical latches or doors, connectors,etc.—may be eliminated, allowing the size of the sound processor to besmaller and removing potential failure mechanisms.

In a preferred embodiment, the integrated power source comprises arechargeable battery. However, other replenishable power sources mayalso be used, e.g., ultra or super capacitors, in place of arechargeable battery, or to supplement a rechargeable battery.

Additionally, it should be noted that as battery technology improves (orcompatible technology associated with other power sources becomesavailable), and as the cost of manufacturing the circuits within a soundprocessor decreases, a point will some day be reached where it makeseconomic sense to make a disposable (or recyclable) external soundprocessor. That is, when the energy capacity of the power source withinthe sound processor is such that the device can be reliably operated forone or two or more weeks, and the cost of manufacturing and/or recyclingthe sound processor has been sufficiently reduced, then the user cansimply be provided with a supply of body-worn sound processors. When theintegrated power source of a given sound processor has been depleted,then the user simply starts using a new sound processor and throws thedepleted sound processor away, or (more preferably) sends the depletedsound processor back to the manufacturer for recycling.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following more particulardescription thereof, presented in conjunction with the followingdrawings wherein:

FIG. 1 is a block diagram of a prior art cochlear implant system;

FIG. 2 shows a representative prior art behind-the-ear (BTE) soundprocessor with its associated headpiece;

FIG. 3 is a block diagram of an externally-worn sound processor withintegral replenishable power source made in accordance with the presentinvention;

FIG. 4 shows the sound processor with integral power source of thepresent invention and further illustrates various detachable interfacemodules that may be used therewith;

FIG. 5 depicts the manner in which the integral power source of thesound processor may be recharged using a base station; and

FIG. 6 shows an alternative type of base station that may be used torecharge the power source within the sound processor.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

Referring first to FIG. 1, a block diagram of a prior art cochlearimplant system 10 is shown. The system 10 includes an implantablecochlear stimulator (ICS) 12 to which an electrode array 14 is attached.The electrode array 14 includes a multiplicity of electrode contacts(not shown) through which electrical stimulation may be applied totissue and nerves within the inner ear (cochlea) of a user of thedevice. The ICS 12 and electrode array 14 are designed to be implantedbeneath the surface of the skin 15 of the user.

External (not implanted) components of the system 10, also shown in FIG.1, include a headpiece 20, a sound processor 30 and a power source 40. Amicrophone 32 is connected to the sound processor 30. Also typicallyincluded as part of the sound processor 30 are manual controls 34,usually in the form of knobs or buttons, that allow the user to adjustcertain parameters of the sound processor 30.

The power source 40 is detachable from the sound processor 30 andprovides the operating power for the system 10. The power source 40typically comprises primary batteries that can be thrown away whendepleted and replaced with new batteries, or rechargeable batteries thatcan be recharged.

The sound processor 30 receives sound signals through the microphone 32and processes such signals to convert them to stimulation signals inaccordance with a selected speech processing mode that is programmedinto the sound processor. The resulting stimulation signals are thenapplied to a coil 22 in the headpiece 20.

The coil 22 of the headpiece 20 is coupled, either inductively orthrough an RF link, to another coil (not shown) in the ICS 12, therebyallowing the stimulation signals to be received by the ICS. Thestimulation signals typically comprise a carrier signal (which, whenreceived in the ICS is rectified and used to provide operating power forthe ICS circuits) that is modulated with control information, i.e.,information that designates which electrode contacts are to receive astimulating pulse, and the intensity and timing of such pulse.

A more complete description of representative cochlear stimulationsystems may be found in U.S. Pat. Nos. 5,603,726; 5,824,022; 6,219,580;and 6,289,247, each of which is incorporated herein by reference. A moredetailed description of a representative cochlear electrode array 14that may be used with a cochlear stimulation system may be found in U.S.Pat. No. 6,129,753, also incorporated herein by reference.

The sound processor 30 used with a cochlear stimulation system 10 maycomprise a body-worn device, e.g., one that is fastened to the user byway of a belt clip, or carried in a pocket of the user, or one that ispositioned behind the ear of the user.

FIG. 2 shows a representative prior art behind-the-ear (BTE) soundprocessor 30′ with its associated headpiece 20′. A microphone may becarried within the headpiece 20′, with sound passing through a suitableopening 33 of the headpiece to the microphone. Alternatively, themicrophone may be built-in to the BTE sound processor 30′, or connectedto the sound processor 30′. Manual controls 34 are typically locatedalong a back edge of the BTE unit 30′. The BTE sound processor 30′includes an ear hook 36 that allows the body of the processor 30′ to behung behind the ear of the user. A detachable battery door, or batterymodule 42, is located at the lower portion of the body of the processor30′. A boundary line 43, emphasized as a heavy line in FIG. 2, defineswhere the battery door begins. Typically, there is a latch, or othermechanism, that allows the door to be opened when the battery carriedtherein needs to be removed and replaced. Additionally, because thebattery is replaceable, there must be suitable contacts, or connectors,inside the battery compartment that allow the battery, or batterymodule, to make reliable electrical contact with the sound processingcircuits housed within the main body portion of the sound processor 30′.Such latches or mechanisms, as well as the contacts, or connectors, allconstitute additional elements that could misalign, malfunction orbreak, thereby adversely impacting the reliability of the BTE unit 30′,as well as components that take up valuable space within the soundprocessor, thereby rendering the BTE unit 30′ larger and more complexand perhaps heavier than it needs to be.

FIG. 3 is a block diagram of an externally-worn sound processor 50 madein accordance with the present invention. The sound processor 50includes sound processing circuits 52 coupled to a suitable microphone54, or other sound source, and a headpiece 20. Also included as part ofthe sound processor 50 is a replenishable power source 60 that isintegral with, i.e., included within, the sound processor 50. Acharging/communication coil 56 and one or more sensor modules 58 areadditionally included as an integral part of the sound processor 50.

The replenishable power source 60, in a preferred embodiment, comprisesa rechargeable Lithium-Ion battery. Other types of rechargeablebatteries may also be used. The Lithium-Ion battery is preferred, basedon present battery technology, because of its high energy-densitycharacteristics, and its ability to receive numerous recharges. Asuitable Lithium-Ion battery for this BTE sound processor applicationmay be obtained from Quallion of Sylmar, Calif.

Still with reference to FIG. 3, the charging/communication coil 56provides a means through which a charging signal may be received from anexternal source for the purpose of recharging the power source 60. Suchcoil 56 also provides a means through which a radio frequency (RF) link72 may be established between the sound processor 50 and a remotecontrol device 70 and/or a radio frequency (RF) link 82 may beestablished between the sound processor 50 and a programming device 80.Alternatively, some embodiments of the invention may utilize a remotecontrol device 70 and/or a programming device 80 that establishes anoptical link, e.g., an infra-red link, with the sound processor 50, oran acoustic link, e.g., an ultrasound or other acoustic link. An exampleof one type of remote control device 70 that could be used with theinvention is disclosed, e.g., in U.S. patent application Ser. No.09/981,252, filed Oct. 16, 2001, incorporated herein by reference, whichapplication is assigned to the same assignee as is the presentapplication.

The remote control device 70 provides a means whereby the user maychange the operating parameters of the sound processor 50 without theneed for manual controls, as have been used in the past. Advantageously,the remote control device 70 may be very small so it can be carried on akey chain, worn on a necklace, or held in a pocket or coin purse.Alternatively, or conjunctively, a relatively large remote controldevice 70 may be provided that has easy-to-read large controls thereonthat can be easily seen and used by the elderly, or others who mayneither have good eyesight nor good manual dexterity.

The programming device 80 allows programming of the sound processor 50and ICS 12. Typically, the programming device 80 is a laptop computer,hand held computing device, or equivalent processor, or is an interfaceunit that is coupled to a suitable computer. Through use of such device,all of the key operating parameters of the cochlear implant system 10may be set and monitored, as is known in the art. See, e.g., U.S. Pat.Nos. 5,626,629; 6,219,580 and 6,289,247, incorporated herein byreference.

It is thus seen from FIG. 3 and its accompanying description that acochlear implant system 10′ made in accordance with the presentinvention includes: (1) an implantable portion 12; (2) an externalportion comprising the headpiece 20 and the sound processor 50; (3) aremote control unit 70 adapted to electromagnetically communicatethrough a recharging/control coil 56 so as to allow operating parametersof the sound processing circuits to be selectively adjusted; and (4) abase station 90 (see FIG. 5) having recharging circuitry housed thereinadapted to recharge the rechargeable battery of the sound processor 50through the recharging/control coil 56 when the sound processor 50 isplaced in close proximity to the base station 90. It is further seenthat the sound processor 50 comprises the microphone 54, the soundprocessing circuits 52, the rechargeable battery 60 and arecharging/control coil 56 integrally housed within a closed case.

It is further seen from FIG. 3 and its accompanying description that asound processor 50 made in accordance with the present inventionincludes: (1) a microphone 54 adapted to receive sound signals andconvert them to electrical signals; (2) a sound processing circuit 52adapted to receive the electrical signals from the microphone 54 andconvert them to a stimulation signal, and further adapted to generate apower signal; (3) a headpiece 20 connected to the sound processingcircuit 52 through which the stimulation signal and the power signal aretransferred by a coil 22 to an implantable cochlear stimulator 12; (4) areplenishable power source 60 integrally housed within the soundprocessor 50 that provides operating power for the sound processingcircuit 52 and implantable cochlear stimulator 12; and (5) a coil 56integrally included within the sound processor 50 and coupled to thesound processing circuit 52 and replenishable power source 60 throughwhich power from an external charging source is selectively received torecharge the replenishable power source 60 when the sound processor 50is in proximity to the external charging source. Moreover, it is seenthat the coil 56 and sound processing circuit 52 are further adapted toreceive external control signals from an external source that controlthe operation of the sound processing circuits 52.

FIG. 4 shows a plan view of the sound processor 50 of the presentinvention, and further illustrates various detachable interface modulesthat may be used therewith. As seen in FIG. 4, in one embodiment, theear hook 36 comprises a detachable microphone assembly 36 a. Suchassembly 36 a includes a microphone 54′ at the end of a boom 37. Theassembly 36 a may be detachably secured to the upper end of the soundprocessor 50, either with a snap-on connection or a screw-on connection.

A second interface module 36 b that may be detachably secured to thesound processor 50 comprises a module that includes a visual indicator38, e.g., a light emitting diode (LED), that provides visualconfirmation of the functionality of the sound processor 50. Such module36 b is particularly well suited for very young users who may not beable to communicate regarding how well the system is working. Theparents and teachers of such young users can, by looking at theindicator 38, determine whether or not the cochlear implant system is ONand functioning.

A third interface module 36 c that may be detachably secured to thesound processor 50 comprises a module that includes a telecoil 39therein that facilitates telephone communications.

A fourth interface module 36 d that may be detachably secured to thesound processor 50 comprises a module that includes a miniaturetelephone jack 41, or other suitable connector, for connecting with anauxiliary device, e.g., the headphone connection of a CD player, MP3player, radio, TV, Cell phone, computer, or other handheld audio device.

FIG. 5 depicts the manner in which the integral power source 60 of thesound processor 50 may be recharged using a base station 90. Theembodiment of the base station 90 shown in FIG. 5 includes a primarypower source 94, which may comprise a primary battery, e.g., aconventional “D” size battery or combination of “D” size batteries, orwhich may comprise a power supply connected through a plug 95 with asuitable ac power source. In some embodiments, both a primary batteryand an ac power source may be used, with the battery providing theoperating power used by the base station (including the powertransferred to the power source 60 of the sound processor 50) when no acpower source is available, as might occur, for example when the user istraveling or when there is a power outage.

Also included in the base station 90 is a charging circuit 92 thatreceives power from the primary power source and inductively transferssuch power through a coil 93 in the base station to the coil 56 in thesound processor 50. The circuits 52 in the sound processor 50 directsuch received power to the power source 60 when the sound processor 50is placed in close proximity to the base station. The sensor 58 includedin the sound processor 50 senses when the Processor 50 is placed inclose proximity to the base station. In one embodiment, the sensor 50comprises a magnetic reed switch that is activated by a small permanentmagnet 99 mounted in the base station 90. Control circuits 96, alsocontained within the base station 90, control the charging process basedon feedback signals received from the sound processor 50, e.g., throughthe headpiece 20. In some embodiments, the coil 22 within the headpiece20 is coupled with a coil 97 in the base station 90 in the same manneras coupling occurs with the coil in the ICS 12 when the sound processor50 is in use. When thus connected, diagnostic routines may be carriedout to check the status of the power source 60, and other circuits,within the sound processor 50. The control circuits 96 may further beconnected to one or more visual displays (not shown in FIG. 5) thatsignal to a user the status (e.g., discharged, charging, charged) of thereplenishable power source in the sound processor 50.

FIG. 6 shows an alternative embodiment of the invention wherein a soundprocessor 50′ contains a power source 60 that is directly connected tocontacts 61 and 62 positioned along a bottom edge of the case of thesound processor 50. The sound processor 50′ also includes soundprocessing circuits 52 as previously described. An antenna coil 56′ isalso embedded within the sound processor 50′ in order to allow a remotecontrol unit 70 (FIG. 3) or a programming device 80 (FIG. 3) toestablish a communication link with the sound processor 50′. Thecontacts 61 and 62 may also be used to establish direct electricalconnection with the sound processor 50′ for purposes other than chargingthe battery 60, e.g., for programming.

As further seen in FIG. 6, a base station 90′ is adapted to receive thesound processor 50′. That is, the base station 90′ includes an opening89, or trough, into which the back end of the sound processor 50′ may beinserted. Electrical contacts or terminals 91 a and 91 b are located inthe bottom of the trough 89 and are positioned so as to respectivelyalign with the contacts 61 and 62 of the sound processor 50′ when thesound processor 50′ is inserted into the trough 89 of the base station90′. When thus inserted, so that the contacts 61 and 62 make physicaland electrical contact with the terminals 91 a and 91 b, a chargingcircuit 92′ contained within the base station 90′ may then monitor thevoltage of the power source 60 of the sound processor 50′ and controlthe charge current directed to the power source 60 from a primary powersource 94 in an appropriate manner. Such charging can continue ascontrolled by the charging circuit 92′ without the need for additionalcircuitry within the sound processor 50′.

It is thus seen from FIG. 6, and the above description, that the presentinvention may be further characterized as a cochlear implant system thatcomprises an implantable portion 12 and an external portion, wherein theexternal portion includes a headpiece 20, and a sound processor 50′. Thesound processor 50′ includes sound processing circuits 52, an antennacoil 56′, and a rechargeable battery 60 integrally housed within aclosed case. Further, there are electrical contacts 61 and 62 embeddedwithin, or carried on, a surface of the closed case of the soundprocessor 50′. These electrical contacts connected electrically with therechargeable battery 60 (and may be connected to other locations withinthe speech processing circuits 52). The cochlear implant system furtherincludes, although not shown in FIG. 6 (but understood to be part of thesystem) a remote control unit 70 (see FIG. 3) adapted toelectromagnetically communicate through the antenna coil 56′ to allowoperating parameters of the sound processing circuits 52 to beselectively adjusted. Additionally, the cochlear implant system includesa base station 90′ that has a charging circuit 92′ and a primary powersource 94 and/or 95. The base station 90′ also has electrical terminals91 a, 91 b that are in electrical contact with the charging circuit 92′,and means for holding the sound processor 50′ in such a way that theelectrical contacts 61, 62 of the sound processor 50′ make electricalcontact with the terminals 91 a, 91 b of the base station 90′. When suchelectrical contact is made between the base station 90′ and the soundprocessor 50′, the charging circuit 92′ is connected electrically withthe rechargeable battery 60, thereby allowing the rechargeable battery60 of the sound processor 50′ to be recharged from the primary powersource 94 and/or 95 of the base station 90′.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

1-20. (canceled)
 21. A sound processor for use with an implantablecochlear stimulator configured to receive stimulation signals, the soundprocessor comprising: a microphone configured to receive sound signalsand convert them into electrical signals; a circuit configured toreceive the electrical signals from the microphone and convert them intoa stimulation signal; a coil operably connected to the circuit andconfigured to transfer the stimulation signal from the circuit to theimplantable cochlear stimulator; and a power source permanentlyintegrated into the sound processor and configured to provide operatingpower for the circuit.
 22. A sound processor as claimed in claim 21,wherein the implantable cochlear stimulator is configured to receivepower signals; the circuit is configured to generate a power signal; andthe coil is configured to transfer the power signal from the circuit tothe implantable cochlear stimulator.
 23. A sound processor as claimed inclaim 21, wherein the circuit comprises a sound processing circuit. 24.A sound processor as claimed in claim 21, further comprising: aheadpiece which carries the coil.
 25. A sound processor as claimed inclaim 21, wherein the power source comprises a replenishable powersource.
 26. A sound processor as claimed in claim 25, wherein thereplenishable power source comprises a rechargeable battery.
 27. A soundprocessor as claimed in claim 25, further comprising: a power coiloperably coupled to the replenishable power source and configured toreceive power from an external charging source and replenish thereplenishable power source when the sound processor is in proximity tothe external charging source.
 28. A sound processor as claimed in claim21, further comprising: a sound processor case that does not include apower source removal door; wherein the circuit and power source arelocated within the sound processor case.
 29. A sound processor asclaimed in claim 28, further comprising: at least one electricalcontact, embedded within or carried on an exterior surface of the soundprocessor case, electrically connected to the power source.
 30. A soundprocessor as claimed in claim 21, further comprising: means for mountingthe microphone, circuit and power source behind a human ear.
 31. Acochlear implant system, comprising: an implantable cochlear stimulator;and an external sound processor including a closed case and a soundprocessor circuit, a coil and a rechargeable power source integrallyhoused within the closed case.
 32. A cochlear implant system as claimedin claim 31, further comprising: at least one electrical contact,embedded within or carried on an exterior surface of the closed case,electrically connected to the rechargeable power source.
 33. A cochlearimplant system as claimed in claim 31, further comprising: a power coiloperably coupled to the rechargeable power source and configured toselectively receive power from an external charging source and rechargethe rechargeable power source when the sound processor is in proximityto the external charging source.
 34. A cochlear implant system asclaimed in claim 31, wherein the implantable cochlear stimulator isconfigured to receive power signals; the sound processor circuit isconfigured to generate a power signal; and the coil is configured totransfer the power signal from the sound processor circuit to theimplantable cochlear stimulator.
 35. A cochlear implant system asclaimed in claim 31, further comprising: a headpiece that carries aheadpiece coil and a microphone.
 36. A cochlear implant system asclaimed in claim 31, wherein the external sound processor includes amicrophone configured to receive sound signals and convert them intoelectrical signals; the sound processor circuit is configured to receivethe electrical signals from the microphone and convert them into astimulation signal; and the coil is operably connected to the soundprocessor circuit and configured to transfer the stimulation signal fromthe sound processor circuit to the implantable cochlear stimulator. 37.A cochlear implant system as claimed in claim 31, further comprising: aremote control unit configured to electromagnetically communicate withthe external sound processor.
 38. A cochlear implant system as claimedin claim 31, further comprising: a base station configured to charge therechargeable power source.
 39. A cochlear implant system as claimed inclaim 31, wherein the closed case does not include a battery removaldoor.